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Biomedical subjects

R H Smith

Publications and source records attributed to R H Smith.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Drugs of abuse in saliva: a review.

There has been substantial interest in the use of saliva as a diagnostic medium for drugs of abuse because it can be obtained noninvasively. Although drugs of abuse have been investigated in saliva for more than a decade, the role of saliva remains uncertain. A clear picture is difficult to obtain because of variations in (1) the analytical methods used; (2) the dose regimen of subjects, which was either unknown or differed between studies; and (3) the elapsed time between drug intake and sample collection. This communication summarizes the studies on the quantitative determination of different drugs of abuse in saliva to elucidate the current status in this area. Marijuana, cocaine, phencyclidine, opiates, barbiturates, amphetamines, and diazepines (or their metabolites) have all been detected in saliva by various analytical methods, including immunoassay, gas chromatography/mass spectrometry, and thin layer chromatography. Initial studies with cocaine and phencyclidine suggest a correlation between saliva and plasma concentrations of these drugs, indicating a dynamic equilibrium between saliva and blood. Tetrahydrocannabinol, the active component in marijuana, on the other hand, does not appear to be transferred from plasma to saliva. However, tetrahydrocannabinol is sequestered in the buccal cavity during smoking and can be detected in saliva. These findings point to the potential role of saliva in the analysis of many illicit drugs. To clearly identify the role of saliva as a diagnostic medium for drugs of abuse, research efforts should be directed towards (1) performing systematic studies on correlations between saliva, blood, and urine and (2) determining the concentrations of drugs and their metabolites in saliva as a function of dose and time after intake.

Female↗
PubMedDate not supplied

Comparison of fixed and adjustable window width and level settings in the CT evaluation of diffuse lung disease.

OBJECTIVE: The purpose of this investigation was to assess the utility of allowing free adjustment of window width and level in comparison with the use of a fixed lung window in the CT evaluation of diffuse lung disease. MATERIALS AND METHODS: Six radiologists each judged 36 cases (28 diffuse lung disease and 8 normal) using a standardized form. In half of the sessions, images were viewed in a fixed lung window (level = -500 HU; width = 2,000 HU). In the other sessions, the observer was able to adjust the window and level freely while viewing the images. Each case was seen twice in separate sessions: once in a fixed lung window and once with window width and level adjusted by the reader. A variety of diagnostic features were evaluated using a 5 point scale. These included visibility of fine lung structures, abnormalities of the lung parenchyma, and overall evaluation of the lung. RESULTS: The visibility of lung structures was not improved with adjustable window settings. Receiver operating characteristic (ROC) analysis showed fixed windows to be superior to adjustable windows for overall evaluation of the cases [fixed A(z) = 0.90, adjustable A(z) = 0.84, p < 0.05, jackknife method]. Time to rate each case was increased by 15% with window width and level adjustment. CONCLUSION: Free adjustment of window width and level produced no improvement in reader performance over that achieved with fixed window width and level.

Humans↗
PubMedDate not supplied

Interobserver variability in the interpretation of unenhanced helical CT for the diagnosis of ureteral stone disease.

PURPOSE: The purpose of this study was to analyze interobserver agreement in the interpretation of unenhanced helical CT (UHCT) for the evaluation of ureteral stone disease and obstruction. METHOD: One hundred three UHCT examinations were independently and retrospectively reviewed by five readers including attending radiologists, a radiology resident, and an attending urologist. Examinations were interpreted as positive, negative, or indeterminate for ureteral stone disease and obstruction. The Cohen kappa test was used to measure interobserver agreement. The accuracy of the readers was also assessed. RESULTS: The kappa value ranged from 0.67 to 0.71 among the three attending radiologists and from 0.65 to 0.67 among the radiology attending physicians and radiology resident. Although the urologist tended to agree less well with the other readers (kappa range: 0.33-0.46), there was no statistically significant difference (p < 0.05) in the accuracy among all five readers. The percentage of cases interpreted as indeterminate ranged from 8 to 25% and almost invariably involved difficulty distinguishing phleboliths from minimally obstructing distal ureteral calculi. The percentage of UHCT scans correctly interpreted as positive and correctly interpreted as negative ranged from 73% (n = 27) to 86% (n = 32) and 63% (n = 22) to 86% (n = 30), respectively. CONCLUSION: Interobserver agreement was very good among the radiology attending physicians and resident and moderate with the urologist. The examination is an accurate technique in the evaluation of ureteral stone disease, although limitations exist, particularly in the diagnosis of minimally obstructing distal ureteral calculi.

Abdominal Pain↗
PubMedDate not supplied

Electroanesthesia (EA) studies: EA produced by stimulation of sensory nerves of the scalp in Rhesus monkeys.

After it was learned that electroanesthesia (EA) could not be produced in a Rhesus monkey which had undergone a circumferential scalp block with 0.25% lidocaine, it was postulated that EA could be produced by electrostimulation of the sensory nerves of the scalp in the rhesus. The work reported here verifies that EA can be produced by this method in this species; it is not necessary to pass current through the head.

Animals↗
PubMedDate not supplied

Primary what?

What is meant by 'primary care' Is it peculiar to nursing? Is it concerned with Primary Health Care? The authors delivered this paper at one of the Special Interest sessions in Tel Aviv at the Quadrennial Congress and stimulated the audience to much thought. Are we sure we are always talking about the same thing?

Humans↗
PubMedDate not supplied

Electroanesthesia (EA) studies: current applications to human volunteers to produce general and local anesthesia.

Electrical currents found to be of sufficient intensity to produce EA in animals were applied to human subjects several hundred times, to determine whether, and how, clinical general anesthesia, and local anesthesia in various parts of the body, could be obtained. General anesthesia was not produced in any subject in any test, the obstacle in every instance being pain. Local analgesia of the arm was obtained in one subject, but in all other subjects muscle spasm and vibration pain prevented application of enough current to produce analgesia or anesthesia in the arm. Anesthesia of the hand was produced several times in all subjects, with a total loss of pain sensation.

Analgesia↗